SCN5A Variant T644I Detail

We estimate the penetrance of LQTS for SCN5A T644I around 14% and the Brugada syndrome penetrance around 21%. SCN5A T644I was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. T644I is not present in gnomAD. T644I has been functionally characterized in 0 papers. This residue is located in a Mild_Hotspot region for Brugada syndrome and a Mild_Hotspot region for LQTS. In silico predictions, functional data (if available), and location in structure are equivalent to phenotyping 10 individuals for Brugada syndrome (2 diagnosed with Brugada syndrome) and 5 individuals for LQTS (0 with LQTS). These data combined with observations of carriers lead us to estimate the LQTS penetrance for SCN5A T644I around 14% (0/10) and the Brugada syndrome penetrance around 21% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.561 27 17
PROVEAN scores less than -2 are considered deleterious. REVEL scores higher than 0.5 or 0.75 are considered likely pathogenic (higher sensitivity with the former cutoff, higher specificity with the latter cutoff). A PolyPhen-2 score of 0.85 or greater is considered likely pathogenic. BLAST-PSSM reflects the evolutionary conservation of residue substitutions, more negative numbers indicate fewer observations of the specific substitution than is expected. Penetrance Density is our previously published method to calculate the average BrS/LQTS probability density in a shell of residues surrounding a residue of interest (Kroncke et al. 2019).

Reported Carrier Data

PubMed ID Year Carriers Unaffected LQT3 BrS1 Other Other Disease
LITERATURE, COHORT, AND GNOMAD: - 0 0 0 0 -
VARIANT FEATURES ALONE: - 15 13 0 2 - -
Summary totals might not agree with the literature table because of duplicate patients, which were excluded from the total counts. We do not distinguish here between multiple missense codons. Missense variants are combined across degenerate codon substitutions since codon-level data were not consistently available for curation.

T644I has 31 previously observed neighbors within 15 angstroms

A residue within a folded protein on average has nearest neighbors that fall roughly into two shells: a "nearest" neighbor around 5-6 angstroms and a second shell around 11 angstroms. All variants shown in the rightmost column have been observed in at least one individual in the literature or gnomAD.

Neighbor Distance (Angstroms) Variants Observed in Individuals
629 15 D629Y,
630 14 T630M,
631 14 c.1890G>A, c.1890+5G>A, p.T631VfsX101,
632 13 T632M,
633 13
634 12 S634W, S634L,
635 11
636 11 E636K,
637 10 P637L,
638 9 G638D,
639 8 G639R, G639A,
640 8 P640S, P640L, P640A,
641 7
642 5
643 4
644 0
645 4
646 5 p.Q646RfsX5, c.1936delC,
647 7 A647D, A647V, A647S,
648 8 P648L,
649 8 C649Y, C649R,
650 9
651 10 c.1950_1953delAGAT, D651H,
652 11 G652S, G652D,
653 11
654 12 E654K, E654Q, E654X , E654D,
655 13 E655K,
656 13 P656L,
657 14
658 14 A658V,
659 15 R659W, R659Q,